It's the third state to outlaw the practice; others are considering similar bills

Illinois has become the third state in the country to pass a law prohibiting companies from asking employees and job candidates for usernames and passwords to their social media accounts.

Illinois Gov. Patrick Quinn signed the bill amending the state's existing 'Right to Privacy in the Workplace Act,' into law last week.

The amendment goes into effect Jan. 1 and makes it unlawful to "request or require any employee or prospective employee to provide any password or other related account information" to any social media networks to which they might belong.

The bill does not limit employers from lawfully monitoring employee computers and emails. Nor does it limit them from seeking or reviewing publicly available information about a person from social media sites. The ban on access to worker's social media profiles applies even in situations where a job might require comprehensive background screening.

Illinois follows Maryland and Delaware in passing such a law. Several other states, including California, Massachusetts, Michigan, New York and Washington are considering similar legislation.

The laws are being prompted by what some see as a disturbing trend among employers and educational institutions to ask current and future workers for access to their social media profiles as a condition of employment.

Maryland's bill signed into law by Gov. Martin O'Malley in May, for instance, was prompted by an incident involving a state Division of Corrections worker who was asked to provide his Facebook login credentials during a recertification interview.

The incident drew considerable criticism from the local chapter of the American Civil Liberties Union (ACLU), which called it a violation of the worker's First Amendment rights to free speech

In a report earlier this year, the Council of State Governments (CSG) recounted another incident in which an elementary school teacher's aide in Michigan was suspended, and then fired, for refusing to provide access to her Facebook account. That request came after a parent reported seeing an inappropriate photo of hers on Facebook.

The teacher has sued the school district for wrongful termination.

"People have been asked to delete their social media accounts, 'friend' a human resources director or coach, or even hand over the username and password of a personal account," the CSG report said. "The latter could mean the employer or school administrator could view very personal information about the individual in question, including, for example, his or her history of Facebook messages."

According to the CSG, employers and educational institutions have begun taking "extra steps to access information hidden behind the privacy walls that users erect," on social media sites.

The trend has attracted the attention of federal lawmakers as well. In March, Sens. Richard Blumenthal (D-Conn.) and Charles E. Schumer (D-N.Y.) called on the U.S. Department of Justice to investigate whether the practice violates the Stored Communication Act or the Computer Fraud and Abuse Act.

In an open letter to U.S. Attorney General Eric Holder, the two lawmakers noted that requiring employers and job applicants to provide login credentials to private social media accounts "may be unduly coercive and therefore constitute unauthorized access under both SCA and the CFAA."

Facebook itself has expressed concern over the issue. In a blog post earlier this year, Erin Egan, Facebook's chief privacy officer noted a "distressing increase" in reports about employers and others seeking access to social media accounts. "The most alarming of these practices is the reported incidents of employers asking prospective or actual employees to reveal their passwords," Egan noted.

Such requests are not only wrong, but also a violation of Facebook's privacy rules, Egan noted.